An iron-based alloy containing carbon, and other alloying elements eg manganese. Steel contains anywhere between 0.2% carbon for soft wire and sheet steel and 1.5% carbon for cutting tools.
A work in progress as I add descriptions and data about the various types of steel.
Low carbon free cutting mild steel. Good machining qualities. Also known as: 230M07, AISI 1213
A medium tensile strength steel with a carbon content of 0.4 to 0.45%. The mechanical properties are just above those of mild steel. Can be heat treated to improve surface hardness. Also known as 080A40
Manganese molybdenum steel with good ductile and mechanical strength and the ability to withstand shock loading. Uses include: High tensile shafts, bolts and gears. Also known as: 605M36T
A nickel chrome molybdenum steel with good ductile and tensile strength with good shock and wear resistance properties. Also known as: 817M40T
Used a lot for cutting tools.
The image to the right shows some blank pieces ready to be ground to shape and then used as lathe cutting tools.
Steels which are known for possessing superior strength and toughness without losing malleability, although they cannot hold a good cutting edge.
Used to cover a wide range of specifications and forms for a variety of Steels – in general it is used to describe steels that can be used in not very demanding applications.
A single throw crankshaft machined from mild steel.
Hardening: Mild steel can be case hardened to increase the surface hardness. Case hardening can be difficult to get hold of, but EKP Supplies Beta 1 compound.
Oil Hardening Steel: Heat the steel to 770 to 800°C and soak at this temperature for 3/4 hour per inch (25.4mm) thickness of material. Quench in a bath of oil inserting the heaviest end of the piece first (this way relieves stresses and reduces distortion). Further heat treatment at 100 to 120°C for a short while and then allowing the piece to cool naturally in air will reduce the stresses further and the possibility of cracking. Note: the higher the carbon content the lower the hardening temperature of steel.
Steel manufactured under the specifications by the Society of Automotive Engineers.
There are a lot of uses for silver steel and a lot of these are because it is easy to harden. Also, silver steel is readily available in both metric and imperial round bar that is very accurate and so great for axles. Cutting speeds for silver steel, these are just an indication but they are a good starting point.
A range of stainless steels are available that have varying degrees of resistance to corrosion, containing between 8 and 25% Chromium. Other elements used in Stainless Steel are Nickel and Niobium.
Machining: Keep the surface speed down to prevent work hardening. Work hardening can sneak up fast when machining stainless and so the default method is to go slow with a generous feed. Work hardening can also occur if the tool rubs on the surface.
The goal with the slow surface speeds is to reduce the work hardening. The goal of the higher feed rates is to make sure you are cutting a good distance under the surface that was previously cut to hopefully avoid having the cutter engage the hard surface.